Dual mode spiral antenna



Aug. 11, 1964 K. DOLLINGER 3,144,648

DUAL MODE SPIRAL ANTENNA Filed Sept. 28, 1962, r 4 Sheets-Sheet 1 Q N Fls 24 28 FIG. 3 33 X I HYBRID I JUNCTION w 7O AMPLFER 3O 29 l DUPLEXER27 x I :jjfj SINGLE LOBING 1 T SIDE BAND IRATE AMPUF'E IlWfi'L E E ITGENERATOR GENERATOR 3| I 6 DIRECTIONAL COUPLER KENNETH DOLLINGERINVENTOR.

ANGLE 9 r RECE'VER 4 DEMGDULATOR BY M IG. r ATTORNEY Aug. 11,

Filed Sept. 28, 1962 1964 K. DOLLINGER 3,144,648

DUAL MODE SPIRAL ANTENNA 4 Sheets-Sheet 2 I TRANSMITTER 69 fDuPLExER 4|ALMDDE I T L A HYBRID p w 45 JUNCTION DIvIDER 2 l MODE 1 I X 40 42 POWER7 ELEvATIoN ag DIVIDER JUNCTION SHIFTER I I 6| A &\ FIG. 5 AZIMUTHELEVATION 44 3 HYBRID DETECTORS JUNCTION 59!) 60 AZIMUTH DETECTORSAMPLITUDE .n 0 +11 ANGLE OF DISPLACEMENT FROM PERPENDIcuL R F l (5.6

LIJ (D 3: I 48 0 g I E J 6:

qr +1r SIGNAL DIRECTION IN PLANE KENNETH DOLLINGER OF SPIRAL INVENTORFIG? ATTORNEY g- 19.64 K. DOLLINGER 3,144,648

DUAL MODE SPIRAL ANTENNA Filed Sept. 28, 1962 4 Sheets-Sheet 5 MASKlNG vw 2 SIGNAL HYBRID GENERATOR 55 JUNCTION A STG HEL GENERATOR s4 5|AMPLITUDE 11 Y 0 15 OFFSET ANGLE FIG19 A) MODE N TRANSMITTER/ HYBRIDKENNETH DOLLINGER INVENTOR.

BY mx 40M ATTORNEY Aug. 11, 1964 Filed Sept. 28, 1962- K. DOLLINGER3,144,648

DUAL MODE SPIRAL ANTENNA 4 Sheets-Sheet 4 f If I CURRENT DISTRIBUTIONSON SPIRAL DURING ONE-HALF R.F. CYCLE FIG.IIC

REFERENCE POINTS FOR VERTICAL POLARIZATION PATTERN DISPLACEMENT FIG.'I2

REFERENCE POINTS FOR HORIZONTAL POLARIZATION PATTERN DISPLACEMENT FIG.l4

DISPLACEMENT OF VERTICALLY POLARIZED PATTERN F I GQIB DISPLACEMENT OFHORIZONTALLY POLARIZED PATTERN F I |5 KENNETH DOLLINGER INVENTOR.

BY 9 4M ATTORNEY United States Patent 3,144,648 DUAL MODE SPIRAL ANTENNAKenneth Dollinger, Nashua, N.H., assignor to Advanced DevelopmentLaboratories, Inc., Nashua, N.H., a corporation of Delaware Filed Sept.28, 1962, Ser. No. 226,915 17 Claims. (Cl. 343-100) The presentinvention relates to wave translation devices. More particularly, theinvention relates to wave translation devices having directionalcharacteristics for transmission and reception. More especially, theinvention relates to novel wave translation devices and systemsutilizing dual mode excitation of a so-called spiral antenna.

In the prior art, a number of systems have been proposed for directionalwave transmission and reception of electromagnetic energy in a formtypically termed conical scanning. The directional pattern oftransmission or reception is produced by the apparent motion of anolfset beam rotating about the bore sight axis to provide a cone ofradiation with very fine discrimination along the bore sight axis.

In the past, conical scanning has been accomplished primarily bymechanical means. Thus, for example, an eccentrically mounted dipole maybe rotated about an axis. In patents numbered 2,878,470, 2,818,563,issued to Jesse L. Butler on March 17, 1959, and December 31, 1957,respectively, a system is disclosed and claimed wherein the apparentrotation of the beam takes place at three times the mechanical rotationof the wave translation element.

In such conical scanning systems of the prior art, the rate of rotation,i.e., the conical scanning frequency, is limited to the rate attainableby mechanical means. The wave translation device of the presentinvention may be used for conical scanning without any mechanical movingparts. The generation of conical scanning rates in this form of theinvention may be accomplished electrically. In this manner,extraordinarily high conical scanning frequency may be accomplished witha resultant extraordinary increase in information rate.

Prior art conically scanning antennas present severe problems in thereception of circularly polarized energy. An important advantage of theinstant invention lies in greatly improved reception of circularlypolarized energy. This is particularly important for large antennainstallations.

In general, the prior art antennas useful for conical scanning arefrequency-sensitive. The frequency response of such antennas isrelatively narrow; off the center frequency the efliciency of such priorart antennas rapidly degenerates. In contrast, the present wavetranslation device of the present antenna has a relatively broadfrequency response pattern.

Another feature of the invention relates to its application to so-calledmonopulse radar systems. The prior art monopulse system is typicallycharacterized by four separate wave translation or antenna systems. Incontrast, the wave translation device of the present invention providesa monopulse system with only a single antenna system.

It is highly desirable for some applications of directional wavetranslation to provide a confusing signal in all directions except adesired direction.

The principles of the present invention are applicable to a system fordirective wave translation in which a desired signal may be receivedonly along a preferred direction. In all other directions only aconfused signal may be received. Such a system has broad application forpoint-to-point communication with improved secrecy.

"ice

A further object of the invention is to provide an improved Wavetranslation device capable of high conical scanning frequencies.

Another object of the invention is to provide conical scanning withimproved response to circularly polarized energy.

Still another object of the invention is to provide an improved wavetranslation device useful for monopulse systems.

Yet another object of the invention is to provide an improved wavetranslation device for directional or pointto-point communicationwherein the signal is confused in all directions except a preferreddirection.

Yet another object of the invention is to provide an improved method ofsignaling.

Still another object of the invention is to provide an improved conicalscanning system of simple and economical structure.

Another object of the invention is to provide an improved conicalscanning system having no moving mechanical parts.

In accordance with the invention, there is provided a wave translationdevice. The device includes a pair of curved wave translation elements.Synchronous means are coupled to the elements for coupling the elementsand a pair of signals in synchronous phase relation. Antisynchronousmeans are coupled to the elements for coupling the elements and a pairof signals in phase relation. Variable means are coupled to the elementsfor varying a selected characteristic for one pair of signals relativeto the other pair of signals.

In one form of the invention, the phase of one pair of signals is variedrelative to the other pair.

In another form of the invention the amplitude of one pair of signals isvaried relative to the other pair.

In still another form of the invention the frequency of one pair ofsignals is varied relative to the other pair.

In still another form of the invention, wave translation is providedalong a pair of preferred axes.

In still another form of the invention, deceptive signal means arecoupled to the wave translation elements for translating a deceptivesignal other than. in a preferred direction.

For a better understanding of the invention, together with other andfurther objects thereof, reference is made to the following descriptionof the invention, taken in connection with the accompanying drawings,and its scope will be pointed out in the appended claims.

In the drawings:

FIGURE 1a is a front elevational view of an antenna useful in thepresent invention, and FIGURE 1b is a rear elevational view of theantenna;

FIGURE 2 is a front elevational view of a modification of the antenna inFIGURE 1;

FIGURE 3 is a schematic block diagram of a wave translation systemembodying the invention;

FIGURE 4 is a schematic diagram of a conically scanning wave translationsystem embodying the invention;

FIGURE 5 is a schematic diagram of a monopulse wave translation systemembodying the invention;

FIGURE 6 is a graph illustrating radiation amplitude versus offset anglefor the system in FIGURE 5;

FIGURE 7 is a graph illustrating the relative phase of a dual modesignal versus angle for the system in FIGURE 5;

FIGURE 8 is a schematic diagram of a wave translation system embodyingthe invention as modified for deceptive radiation;

FIGURE 9 is a graph illustrating the operation of the system in FIGURE8;

FIGURE is a transmitter system embodying the invention;

FIGURES 11a, 11b, and 110 are a series of graphs illustrating theantenna current distribution in the operation of the invention;

FIGURES 12 and 13 are graphs illustrating vertical polarization patterndisplacement; and

FIGURES 14 and 15 are graphs illustrating horizontal polarizationpattern displacement.

Principles of Operation The so-called spiral antenna has come intoprominence recently. This antenna characteristically has the structureof a pair of curved wave translation elements. Such an antenna may beexcited in two modes which are characteristically referred to as Lambda(A and Lambda weight High-Powered Spiral Antenna, by J. P. Jones, P. I.Taylor, and C. W. Morrow, published in IRE Wescon Convention Record,page 107, on August 23, 1960, a description of a spiral antenna withdual mode excitation is presented.

In another article'entitled Second Mode Operation of the Spiral Antenna,by John R. Donnellan, published in IRE Transactions on Antennas andPropagation, November 1960, the structure of a dual mode spiral antennais described and its operating characteristics illustrated.

The A mode is excited when the two arms are fed in phase opposition,i.e., a pair of signals are coupled to the wave translation elementswhich are 180 out of phase. The A mode relates to in-phase excitation ofthe wave translation elements. The x, mode exhibits a radiation patternhaving a path along the axis of the spiral or boresight axis of theantenna. The mode exhibits an omnidirectional pattern with a null in thedirection of the boresight axis. It turns out that both of the modes maybe In an article entitled Design Techniques for a Lightexcitedsimultaneously to produce a single lobed beam which is offset from theboresight axis.

It has been proposed that the spiral antenna radiates principally from aband on the spiral surface where the currents in adjacent elements aremost nearly in phase. Thus, if a spiral is fed so that energy enteringthe two spiral elements at the origin are 180 out of phase, the firstcurrent band occurs where the current in one arm returns to an in-phasecondition with the other arm. This condition occurs because of thegeometry of the spiral elements, each successive turn of the spiralbeing progressively longer. On geometric grounds, it would appear thatthe currents of adjacent conductors reach an in-phase condition wherethe circumference of the ring is equal to one wavelength. On the otherhand, if the spiral is fed such that the elements are in phase at theorigin, twice the distance is required for the currents in adjacentconductors to be in phase. It turns out that this condition is realizedwhere the circumference of the effective ring is equal to approximatelytwo wavelengths. The tendency to radiate at the center of the spiral issuppressed by means of a metal plate placed immediately behind thespiral element.

In order to analyze the operation of the antenna with dual modeexcitation, it is useful to consider the antenna to be a combination ofan inner conductor one wavelength long and an outer conductor twowavelengths long. From the following analysis, it will be seen that theresultant antenna pattern indicates that dual mode excitation producesan apparent shift of the center of radiation off the boresight axis.

At time t=0, t= Af and t= /2f, the current distributions are illustratedin FIG. 1111, b and 0. Note that the currents of both elements are inphase where the elements intersect the +X axis. The currents are 180 outof phase at the intersections of the Y axis.

The analysis of the mechanism by which the antenna EQUATION 1 Sin bwhere D=diameter of aperture,

)\=free space wavelength,

J =first-order Bessel function, and

=angle with respect to the normal to the aperture,

minus the effective angular displacement of the point from the focalaxis. The effective angular displacement of the feed point will be about0.8 of the actual angular displacement.

This method of analysis is subject to correction due to coma distortionof the reflector and the directivity of the point feed caused by backingthe spiral antenna'with a reflector or cavity.

A qualitative analysis of the beam displacement effect obtained with thetwo mode spiral as a paraboloidal feed may be obtained as follows:

(1) Assume that for vertical polarization only points on the X-axiscontribute:

A fair approximation for the beamwidth of a paraboloidal antenna isdegrees. For an of 0.4 and a displacement factor of 0.8, the fractionalbeamwidth beam-offset is then about where S is the linear displacementof the feed point from the focal axis.

Referring to FIG. 12, points A, B, C and D are displaced "2 l Z andrespectively. The resulting secondary patterns are then displaced plusand minus one-half and one beamwidth, as shown in FIG. 13. The summationon superposition of these four patterns is a displaced pattern, as shownin FIG. 13.

(2) Similarly, the horizontally polarized patterns may be approximatedcrudely by assuming that only points at Y: \21r contribute. Thus, threepairs of sources E and H, F and I, G and J as shown in FIG. 14 aresummed. The omission of any component from the 2x conductor beyond isjustifiable on the basis that the patterns produced are displaced byclose to a beamwidth in the vertical plane and thus make a negligiblecontribution to the pattern taken on the horizontal axis.

The relative amplitudes of the horizontally polarized components at.points E, F, and G should be respectively /2, 1 and /2. The X-axiscoordinates of the three points are 0 and The horizontal beam offset atpoints E and G should be 1.6 xv? or 0.88 beamwidth. FIG. shows thepattern resulting from the superposition of these three patterns. Thecontributions from E and H are oppositely polarized from thecontributions at F, I, G and J, resulting in a final pattern that isdisplaced to the right of boresight.

It will be apparent, then, that the dual mode spiral antenna using aprimary feed for a parabolic reflector produces an offset secondarypattern. The offset pattern conically scans by continuously varying thephase of the M mode excitation relative to the M mode excitation.

The above analysis indicates that in the M mode, the antenna radiatesprimarily from the vicinity of the inner ring having a circumference ofone wavelength. When the curved element is fed in phase exciting the Mmode, :a double-lobed radiation pattern is produced with null in thedirection of the spiral antenna. This radiation apparently operatesprimarily in the vicinity of the outer ring having a circumference oftwo wavelengths.

Under the condition of dual mode excitation, i.e., both M and M modessimultaneously excited, the resultant pattern is a beam offset from theaxis of the spiral antenna. The direction in which the beam is pointedor the degree of rotation is a function of the relative phase of the Mand M modes of excitation.

Though an offset beam may be obtained from the spiral antenna, this isnot a sufficient condition to produce an offset beam when the spiralantenna is used for a primary radiator for a parabolic reflector. Inorder to produce an offset beam from the combination of a primary spiralantenna and a parabolic reflector, the apparent center of radiation ofthe primary antenna must be displaced from the focal point of thereflector.

From the above analysis, it will be apparent that the center ofradiation of the spiral is apparently displaced off the axis of thespiral when the M and M mode rings are excited simultaneously.Furthermore, it appears that the resultant center of radiation movesabout a circle with its center coinciding with the axis of the spiral asthe phase between the two modes is varied through 211- radians.

An electrically lobed antenna system providing electronic conicalscanning may be obtained by separately exciting the antennasimultaneously with the M and M modes. This may be accomplished byfeeding the spiral at the origin from a Well-knoWn hybrid junction. Thesum arm excites the antenna terminals in phase to produce the M modewhile the difference arm produces the M mode.

The angle of the beam or degree of offset may be varied by adjusting thedegree of coupling between the two modes. A crossover of approximately 3db may be achieved by summing the signals in a 3 db coupler. By looselycoupling the M and M modes, a crossover level of l.0l.50 db may berealized.

Description and Explanation of the Antenna and System in FIGS. 1, 2 and3Referring now to the drawings and with particular reference to FIG. 1,there is here illustrated an embodiment of a spiral antenna. The antennagenerally indicated at 10 has a pair of curved wave translation elements11 and 12. The elements as shown are involute and in the Such a spiralis of the Where R is the radius Vector from the origin to a point on thecurve, 6 the angle of rotation, and k a constant defining the rate ofexpansion of the curve. The elements may be formed from copper foil byWell-known etching techniques. The elements are adhered to a base 13formed of insulating material such as XXXP Bakelite or one of thefluoro-carbons. As shown in the rear view of FIG. 1b, a metal plate 14may be centrally mounted in the vicinity of the inner turns of theantenna to suppress spurious radiation.

In the configuration of FIG. 2 a so-called scimitar antenna isillustrated. The antenna has a pair of scimitar shaped wave translationelements 15 and 16 mounted on a base 17. This antenna is broadly definedto be of equiangular configuration and has the form where R is theradius vector from the origin to a point on the curve, 6 the angle ofrotation, and k a constant defining the rate of expansion of theelement.

Referring now to FIG. 3, there is here illustrated a wave translationsystem embodying dual mode excitation of a spiral antenna. Here a spiralantenna 18 or the type illustrated in FIG. 1 is used as a primaryradiator for a paraboloidal reflector 19. The antenna 18 is situatedwith its center coincident with the focal point of the reflector 19. Thespiral axis perpendicular to its plane is coincident with the axis ofthe reflector 19 and is termed the boresight axis 20. The antenna 18 iscoupled to an excitation source 21 which provides both modes ofexcitation simultaneously. This has the effect of producing an offsetradiation along an axis indicated at 22 for a beam 23 indicated by thedashed line. The angle between the boresight axis 2% and otfset axis 22is determined by the relative amplitude of the M and M modes. As notedabove, the beam 23 may be rotated about the boresight axis 20 by varyingthe phase of the M mode relative to the phase of the M mode to provideconical scanning.

The invention as described herein is taken particularly with respect tothe receive only condition of operation. It is, of course, applicable tothe transmitting case as well. For active conical scanning of thetransmitted beam, the system is reciprocal in concept.

As will be described more completely below, the invention has particularapplication to receive only for monopulse radar tracking systems andconical scanning systems wherein transmission takes place in the M modeand a duplexer protects the receiver.

Description and Explanation of the System in FIG. 4

Referring now to FIG. 4, there is here illustrated a schematic blockdiagram of a conical scanning antenna system embodying the presentinvention. Here a spiral antenna 24 of the type illustrated in FIG. 1provides the primary feed for a paraboloidal reflector 25. The wavetranslation elements 26 and 27 are connected to the input arms of ahybrid junction 28. The hybrid junction is of the type described inHandbook of Tri-Plate Components, page 73, a publication of SandersAssociates, Inc., 1956. The sum or 2 arm ties the M mode to the junction28. The diiierence or A arm ties the M mode to the junction 28.

The arms of the junction 28 are coupled through a pair of amplifiers 31and 33. The amplifier 33 is coupled to a single side band generator 36of the type described in article by A. Clavin, IRE Transactions onMicrowave Theory and Techniques, March 1962, page 98, which derives aninput from a lobing rate generator 29. The generator 29 may be a simpleHartley type oscillator such as described in F. E. T ermans Electronic &Radio Engineering, McGraw-Hill, 1955. The generator 29 produces adisplacement frequency f for the generator 30; The output of the singleside band generator 30 is coupled through a directional. coupler 32 to areceiver 34. The output of the amplifier 31 is. coupled through thecoupler 32 to the receiver 34. The generator 29 and receiver 34 arecoupled to an angle demodulator 35 to produce an indication of thedirection of radiation of the beam.

The antenna 24 is used as the primary feed for the reflector 25. Thehybrid junction couples the x and A modes to feed the elements of theantenna 24 in phase via the sum arm and out of phase via the differencearm. The system as shown is designed to provide passive conicalscanning; that is to say, the system as shown is a receiver. The carrierf is received via the antenna coupled to the junction 28 and separatedinto the two modes x and A The energies are amplified in the amplifiers31 and 33. The output of the amplifier 33 is applied to the single sideband generator 20, which derives another in put from the generator 29.The output of the generator 30 is coupled through the coupler 32 to thereceiver 34. The single side band generator produces an output frequencyf -j-Af displaced from the incoming carrier by the frequency of thelobing rate generator. The A mode signal-is added to the output of thegenerator 30 by means of the directional coupler 32. A resultant signalis produced which is indistinguishable from a prior art conical'scanningantenna having a nutating feed.

The above description relates particularly to a receive only" system;the effect of conical scanning is then passive. A transmitter may beadded for the mode and fed through a duplexer to the antenna. Thus, herethere is shown in dashed lines, indicating a possible addition, atransmitter 69 coupled to a duplexer 70. The duplexer operates totransmit a high power signal only through the antenna 24. On receive,low power energy is coupled from the antenna 24 through the duplexer 70to the amplifier 31.

Description and Explanation of the Monopulse System in FIG.

Referring now to FIG. 5, there is here illustrated a schematic blockdiagram of a monopulse wave translation system embodying the invention.Here a spiral antenna 36, of the type shown in FIG. 1 and having a pairof wave translation elements 37 and 38, provides the primary feed for aparaboloidal reflector 39. The antenna 36 is coupled to a hybridjunction 40. The difference or A arm of the junction 40 is coupled to aM mode power divider 41. The sum or 2 arm couples the mode to the. Amode power divider 42. An output of the divider 42 is coupled to a 90phase shifter 45. Another output of divider 41 is coupled to the azimuthjunction 43. The output of the shifter 45 is coupled to the elevationjunction 44. The outputs of the azimuth hybrid junction 43 are appliedto the azimuth detector crystals through a pair of terminals 59 and 60.The outputs of the elevation comparator 44 are applied to the elevationdetector crystals through a pair of terminals 61 and 62.

As shown in dashed lines, the transmitter 69 is coupled to the duplexer70. The duplexer operates to short out the receiver during transmissionand shunt the energy to the antenna 24. During receive, when thetransmitter is quiescent, the receiver circuit is enabled to receiveenergy from the antenna.

For monopulse application the system utilizes the phase and amplitudecharacteristics of the radiation patterns of the spiral-antenna for dualmode excitation. The amplitude characteristics are illustrated for theplane perpendicular to the plane of the spiral in the graph illustratedin FIG. 6. The curve 46 is the amplitude characteristic of'the A modewith respect to the angle of displacement from the perpendicular to theplane of the spiral. The curve 47 illustrates the amplitude of the xmode with respect to the angle of displacement. By comparing therelative amplitudes of the two modes, the

angle of offset off the axis or the direction of the received signal isindicated.

As shown in FIG. 7, the relative phase between the A and A modes goesthrough 21r radians as the signal direction changes in the plane of thespiral. A comparison of the phases of the signals in both modes providesan indication of the direction of the signal in the plane of the spiral.In the system as illustrated in FIG. 5, the error signals aretransformed into azimuth and elevation information by splitting the Aand A mode signals. One set is compared directly and the second set witha phase shift. In this manner an indication of the projection of thesignal directions with respect to a pair of orthogonal referencedirections in the plane of the spiral is obtained.

This can be seen by considering the behavior of the system for a signalcoming from a direction in the reference plane perpendicular to theplane of the spiral. The phase of the A mode signal with respect to themode signal will remain at zero degrees as the signal direction changesfrom within the plane of the spiral along the reference axes toboresight and will remain at as the signal moves from boresight to theplane of the spiral in a direction opposite to the reference axis. If weassume that the reference axis corresponds to the azimuth axis, then atboresight, the A mode signal is zero sothat equal signals are applied toboth the azimuth and elevation detector crystals. As signal moves towardthe plane of the spiral in the direction of the reference axis,remaining in the reference plane, the x and mode signals will remain inphase. However, the amplitude of the 7., mode signal will'progressivelyincrease. The signals applied to the azimuth detector crystals will beunbalanced in a particular direction. If the signal moves toward theplane of the spiral in a direction opposite to the reference axis, butstill in the reference plane, the A and mode signals will be in phaseopposition and signals applied to the azimuth detector crystals will beunbalanced in the opposite direction. The signals applied to theelevation hybrid will be in quadrature for all the above conditions andthus the inputs to the elevation crystal detectors will remain equal. Ifthe signal comes from a direction in a plane at right angles to thereference plane then the x and x mode signals will be in phasequadrature. Because of the presence of the 90 degree phase shifter 45,the signals applied to the elevation hybrid junction will either be inphase or in phase opposition. Thus unbalanced signals will be applied'tothe elevation crystal detectors and equal signals to the azimuth crystaldetectors.

Description and Explanation of the Deceptive System of FIG. 8

Referring now to FIG. 8, there is here illustrated a schematic blockdiagram of a wave translation system embodying the invention forproviding deceptive signals other than in a preferred direction oftransmission. Here a masking signal generator 49 is coupled to the sumarm of a hybrid junction 50. A true signal generator 51 is coupled tothe difference arm of the junction 59. The output of the junction 56 iscoupled to an antenna 52 of the type illustrated in FIG. 1. The antenna52 with its wave translation elements 53 and 54 provides the primaryfeed for a paraboloidal reflector 55.

A desired signal is generated by the generator 51 coupled to thedifference arm of the junction 53 to be transmitted via the antenna 52and reflector 55 in a preferred boresight direction indicated at 56. Themasking signal generator 49, for example, a noise generator, is coupledto the sum arm of the junction 50 and radiated by the antenna 52 andreflector 55 in the manner indicated by the graph illustrated in FIG. 9.There the curve 57 represents the amplitude of signal with respect tothe offset angle from the boresight axis 56. The masking signal may becomprised of pure noise, other frequencies and random phase and/oramplitude changes to provide deceptive transmission. As indicated inFIG. 9, the curve 58 illustrates the amplitude of the masking signal.This signal has a null on boresight. For this reason the masking signaldoes not interfere with the desired signal in the main lobe of theradiation of the antenna. As noted above, for signal directions off theboresight axis, the masking pattern masks the side lobe transmissions ofthe desired signal.

From the above description it will be apparent that the presentinvention has wide application to the field of wave translation. Thedirectional transmission and reception of signals is greatly enhanced.

While there has hereinbefore been described what are at presentconsidered to be preferred embodiments of the invention, it will beapparent to those of ordinary skill in the art that many and variouschanges and modifications may be made with respect to the embodimentsdescribed and illustrated Without departing from the spirit of theinvention. It will be understood, therefore, that all such changes andmodifications as fall fairly within the scope of the present invention,as defined in the appended claims, are to be considered as a part of thepresent invention.

What is claimed is:

1. A Wave translation device, comprising:

a pair of involute circular, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

variable means coupled to said elements for varying a selectedcharacteristic of one said pair of signals relative to the other saidpair of Signals.

2. A wave translation device, comprising:

a pair of involute curved, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

variable means coupled to said elements for varying a selectedcharacteristic of one said pair of signals relative to the other saidpair of signals.

3. A wave translation device, comprising:

a pair of involute curved, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

variable means coupled to said elements for varying a selected phasecharacteristic of one said pair of signals relative to the other saidpair of signals. 4. A wave translation device, comprising: a pair ofinvolute curved, Wave translation elements; synchronous means coupled tosaid elements for coupling said elements and a pair of signals insynchronous phase relation; 1

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

variable means coupled to said elements for varying a selected amplitudecharacteristic of one said pair of signals relative to the other saidpair of signals.

5. A wave translation device, comprising:

a pair of involute curved, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for Cit ll] couplingsaid elements and a pair of signals in phase relation; and

variable means coupled to said elements for varying a selected frequencycharacteristic of one said pair of signals relative to the other saidpair of signals.

6. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby Wavetranslation along an axis displaced from said normal axis is provided;and

focal directive means coupled to said elements for increasing directiveWave translation along said displaced axis.

7. A Wave translation device, comprising:

a pair of involute curved, Wave translation elements for directive wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby wavetranslation along an axis displaced from said normal axis is provided;and

parabolic focal directive means coupled to said elements for increasingdirective wave translation along said displaced axis.

8. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive Wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby Wavetranslation along an axis displaced from said normal axis is providedand the center of radiation of said elements is displaced from saidaxis; and

focal directive means coupled to said elements for increasing directivewave translation along said displaced axis, said center of radiationbeing displaced from a focus point of said directive means.

9. A wave translation device, comprising:

a pair of involute curved, Wave translation elements for directive Wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby wavetranslation along an axis displaced from said normal axis is provided;

focal directive means coupled to said elements for increasing directivewave translation along said displaced axis; and

variable means coupled to said elements for varying a selectedcharacteristic of one said pair of signals relative to the other saidpair of signals.

10. A wave translation device, comprising:

a pair of involute curved, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

deceptive signal means coupled to said elementsfor translating adeceptive signal other than in a preferred direction.

11'. A wave translation device, comprising a pair of involute curved,wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation; and

variable signal generator means coupled to said elements for varying thephase of one said pair of signals relative to the other said, pair ofsignals, thereby to cause directive wave translation along an axishaving an angular displacement varying in accordance with the phasevariation between said signals.

12. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said, elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling said,elements and a pair of signals in 180 phase relation, whereby wavetranslation along an axis displaced from said normal axis is providedand the center of radiation of said elements is displaced from saidaxis; I

focal directive means coupled to said elements for increasing directivewave translation along said displaced axis, said center of radiationbeing displaced froma focus point of said directive means; and

variable signal generator means coupled to said elements for varying thephase of one said pair of signals relative to the other said pair ofvsignals, thereby to cause angular, displacement of displaced axis inaccordance with, said signal phase variation.

13. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-symchronous means coupled to said elements for coupling saidelements, and a pair of signals in 180 phase relation, whereby Wave.translation along an axis displaced from said normal axis is providedand the center of, radiation of said elements is displaced from saidaxis;

focal directive means coupled to said elements for increasing directivewave translation along said displaced. axiS,,Said center of, radiationbeing displaced from a focus point of said directive means; and

hybrid coupling means coupling said elements, synchronous andanti-synchronous means for coupling said signal pairs.

14. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive wavetranslation. with respect to a normal axis;

synchronous means coupledto said elements for coupling said elements anda pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby wavetranslation along an axis displaced from said normal axis is providedand the center of radiation of said elements is displaced from saidaxis;

focal directive means coupled to said elements for increasing directivewave translation along said displaced axis, said center of radiationbeing displaced from a focus point of said directive means; and

deceptive signal means coupled to said elements for translating adeceptive signal other than along said displaced axis.

15'. A wave translation device, comprising:

a pair of involute, curved, wave translation elements for directive wavetranslation withrespect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in phase relation, whereby wavetranslation along an axis displaced from said normal axis is providedand the center of radiation of said elements is displaced from saidaxis; and

parabolic focal directive means coupled to said elements for increasingdirective wave translation along said displaced axis, said center ofradiation being displaced from a focus point of said directive means.

16. A wave translation device, comprising:

a pair of involute curved, wave translation elements for directive wavetranslation with respect to a normal axis;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation, whereby wavetranslation along an axis displaced from said normal axis is provided;

focal directive means coupled to said elements for increasing directivewave translation along said displaced axis; and

rotary means coupled to said elements for rotating said elements aboutan axis.

17. A wave translation device, comprising:

a pair of involute curved, wave translation elements;

synchronous means coupled to said elements for coupling said elementsand a pair of signals in synchronous phase relation;

anti-synchronous means coupled to said elements for coupling saidelements and a pair of signals in 180 phase relation;

variable means coupled to said elements for varying a selectedcharacteristic of one said pair of signals relative to the other saidpair of signals; and

hybrid coupling means coupling said elements, synchronous andanti-synchronous means for coupling said synchronous and out of phasesignals.

References Cited in the file of this patent UNITED STATES PATENTS2,476,337 Varian July 19, 1949 2,988,739 Hoefer et a1. June, 13, 19612,990,548 Wheeler June 27, 1961 3,013,265 Wheeler Dec. 12, 19613,014,214 Ashby et al Dec. 19, 1961 3,055,003 Marston Sept. 18', 19623,089,136 Albersheim May 7, 1963 OTHER REFERENCES Aviation Week, July14, 1958, pp. 75, 77, 79, 81, 82.

1. A WAVE TRANSLATION DEVICE, COMPRISING: A PAIR OF INVOLUTE CIRCULAR,WAVE TRANSLATION ELEMENTS; SYNCHRONOUS MEANS COUPLED TO SAID ELEMENTSFOR COUPLING SAID ELEMENTS AND A PAIR OF SIGNALS IN SYNCHRONOUS PHASERELATION; ANTI-SYNCHRONOUS MEANS COUPLED TO SAID ELEMENTS FOR COUPLINGSAID ELEMENTS AND A PAIR OF SIGNALS IN 180* PHASE RELATION; AND VARIABLEMEANS COUPLED TO SAID ELEMENTS FOR VARYING A SELECTED CHARACTERISTIC OFONE SAID PAIR OF SIGNALS RELATIVE TO THE OTHER SAID PAIR OF SIGNALS.